TkPNG provides support for PNG image manipulation with Tcl/Tk
and does not depend on libpng.

TkPNG supports the full range of color types, channels and bit depths
from 1 bit black & white to 16 bit per channel full color with alpha
(64 bit RGBA) and interlacing.  Ancillary "chunks" such as gamma,
color profile and text fields are ignored, although they are checked
at a minimum for correct CRC.
